AA is the only oneworld carrier not to offer free booze in Y to all passengers. AA makes a habit of helping its elites pretend that it's a full service carrier. Offering free booze on int'l to PLTs and EXPs would be totally in line with that. As an AAirpass member on the rare occasions I am in coach (thank God for low-mileage, no-copay, int'l upgrades from Y) I am treated generously and with - dare I say - a degree of sympathy, regardless of whether the flight is AE, 2-class mainline, or 3-class mainline. This extends to free drinks/headseats/snacks, use of the closet for extra carryons and coats, and generally better attention and service from the FAs. I really would hope AA extends the same treatment to EXPs, many of whom fly a hell of a lot more than me.
As an EXP, I agree that it would be nice for AA to offer free alcohol in coach to EXP/PLT members on all flights. This is not, however, AA's policy at present and I wouldn't dream of flashing my EXP card to try and get a free drink, thereby potentially putting the FA in an awkward situation. Cough up the $6 or stick to soft drinks when in Y (or pay by credit card and hope the handheld terminal they use isn't working which has often resulted in free drinks without the need to ask

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